DiyLightAnimation
Hardware => Lynx MR16 / 16 CH DC Controller => Topic started by: btdb1969 on March 15, 2012,
-
I built my first MR16, Im using a power supply from a computer. The power supply seems to be working correctly but I have no power LED. I have checked all the solder joints, looked for anthing backwards or incorrectly installed but everything looks right to me. Any help would be very much appreciated. I attached a few photos .
-
No power LED could be that the power LED is in backwards. Have you tried sending DMX to the board? If you don't get it, I would take some photos out in the daylight and from multiple angles.
-
I dont get DMX, I'll take better pictures tomorrow
-
here are the pictures taken in daylight
-
I would test a volt meter setting at the voltage regulator (out) for starters. I assume it's in right but can't see with the heat sink.
-
I would first check to make sure that it is the regulator in the regulator position and not a mosfet since they look the same.
-
Looks like on the POS side of the incoming power that you may have gotten it to hot & possible melted plastic over the metal on the board.
Mike
-
The regulator is in correct and it is the regulator not the mosfet but since im not real good at the technical part, which pins should I touch on the regulator to check it?
-
Here is the data sheet on the regulator. See page 6 for pin outs. Put the ground on the ground pin. Check both the input and output pins for voltage to see if the power is coming in and going out.
http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00000444.pdf
-
This is the only spot I see that looks questionable but one on of the two legs would be affected which should not affect it as they are both soldered into the same pad.
-
@Jeffl
I cleaned up that spot, desoldered it and then resoldered...It still doesnt work
-
How is the voltage at the regulator?
Just and FYI from my experience. A solder station really works well for these spades. I crank the heat up to about 390c and use a wide tip that holds a lot of heat. This way it heats them up quickly. The extended period of heating with low power units can kill parts.
-
I show 12 on the input side, and 0 on the output side...so I take it that it should show 5 on the output side??
...thanks for all the help.
-
Work time is over. It's play time now.
You should have positive voltage on the out as long as the voltage is good on the in. My thought is the voltage regulator is the problem. I'd like to see others chime in that are more experienced than I before you go getting to crazy trying to fix things just in case it could be something else.
-
If you have 12v on one side and don't have 5v on the other, there are only a few things that can cause this.
1. Bad 7805
2. Got one of the mosfets by mistake - if they get mixed together it's hard to tell them apart.
3. Short on the board.
4. 7805 in backwards?
Since this is easy, I'd remove the three chips and see if you still have 0v - one of them could be bad and shorting out the board. I didn't see any solder bridges.
Next, I'd bite the bullet and try to remove the 7805. It's not going to easy though and you are going to need either a really good solder sucker or solder wick... I'd start with just the heatsink first...
RM
-
With the three legged beasts like the regulators, mosfets, and triacs, I usually cut the leads off the device and remove the leads from the board one at a time. If you do that, you'll need to order replacement parts...
RM
-
One thing I always do when I build and Express (now, not when I first started) is install the heat sinks last. I do all the self tests even before installing it. Sorry, but this one is learning experience. Even for the rest of us.
-
I took the 3 chips out, now I have 12v on the input and 1v on the output.... plus the power light is now on
-
Look it over very close for any solder bridges shorting out. It is rare to have a 7805 fail they are very tough as electronic parts go.
RJ
-
Look it over very close for any solder bridges shorting out. It is rare to have a 7805 fail they are very tough as electronic parts go.
Yes, but ... I had a problem building an MR-16 back in 2009 and the root cause was a bad 7805, shipped fresh from M.
So, while the possibility is slim, it isn't non-existent.
\dmc
-
I have looked at this thing about 10 times from different angles under a pretty strong magnifying lens and I dont see any solder bridges.
Since it does have 1v on the output side and the power light DOES come on when i take the three chips out, could one of the chips be bad?
-
if too much solder is applied, sometimes it goes through the hole to the other side and can possible bridge there.
-
At that point I would try a new regulator. If it is a bridge drawing down to 1v I would expect it would be so hot you would have said something about it by now.
RJ
-
I ordered a desoldering pump, Im going to take the sockets off. I cant see under them to tell if there is a bridge there. Thank everyone for your help. I also ordered a new regulator...
-
Before removing the sockets, I would use an ohm meter (DVM) and verify that adjacent pins are not shorted together. Iremove the ICs) There may be pins that are intentionally connected together. Post the pins you find shorted together and other members can help you. This is a lot easier than unsoldering a socket. Unsoldering a socket can potentially damage the board.
-
Unless the regulator is getting really hot like I said I would not expect a bridge and would replace the 7805 regulator.
RJ
-
Are you sure it is a 7805 in that location.
-
yes, it is definately a 7805 in the location
-
It was the 7805, I replaced it and now I have an extreme rainbow working....Thank you everyone for your help in this, I definitely would not have had any ideas on how to fix this on my own. :)
-
Wahoo. Congratulations. Glad to be a part of the journey.